The invention relates to the well-known butted guard band complementary metal oxide semiconductor (CMOS) monolithic integrated circuit (IC) devices. Since relatively heavily doped P and N regions abut each other, the breakdown voltage is relatively low. However, it is often desirable to operate such circuits along with other devices that operate at higher voltages. For example, many circuits are designed to operate from 9-volt batteries and it is often useful and desirable to connect them to CMOS devices. However, the butted guard bands result in a typically 7-volt breakdown. Without current limiting, a 9-volt supply can destroy the devices. On the other hand, the butted guard band form of CMOS construction is often used to make high density ICs which are economical to fabricate and use.
Accordingly, it would be highly desirable to incorporate an on-chip voltage limiter that would reliably avoid overvoltage problems.